Balanced adapter and narrow die for stretching presses



E. M. WELSER April 27, 1948.

BALANCED ADAPTER AND NARROW DIE FOR STRETCHING PRESSES Filed May 8, 1945 2 Sheets-Sheet 1 April 27, 1948. I w s 2,440,529

BALANCED ADAPTER AND NARROW DIE FOR STRETCHING PRESSES Filed May 8, 1945 2 Sheets-Sheet 2 awe/rm Ear/ M. We/ser Patented Apr. 27 1948 BALANCED AND. DIE: FOR

l STRETGHING PRE SSES Earl M. Welser} Akron, Ohio, assignor to Goodyear Aircraft Corporation, Akron, Ohio,

poration of Delaware Anplication May: 8, 1945, SeriaLNo. 5923-3204 l Claims. 1

This invention relates toa draw press of. the pressure cylinder type for stretching and forming sheet. metal, and in particular, to an improvement thereto for. the purpose of increasing the variety of articles to be made thereon.

Hitherto, vertical cylinder and like type draw presses have been used in the aircraft and other industries for forming sheet. metal, parts over shaping dies and. intocompound curves. Howeven. when. the parts have relatively narrow, curved cross-sections and longitudinally curved contoursas, for instance, edges for airplanewings andempennages, these parts could not be produced on standard app atus without stretchin the worlcpicce longitudinally which required special clamping. means for each ifielfi nt cross-s t-ioato be attached to both ends of the work piece. Nor; on the. other hand; could the work piece be drawn on. standard presses in a direction transverse to its length, because the ram beam is too wide and the clampsiior holding. the material are too far apart to be adapted for the production of pieces of narrow cross section. This condition led to special draw press constructions for this purpose. However; because of the larg capital. investment. involved in such specialized machines, the cost of production is raised and valuable floo space is needed. I

Itis the. general. object of the invention to avoid and: overcome theforegoing and other difiiculties of and: objections. to: prior art practices by the provision of a. simple, easily operative and inexpensive device in the form of an adapter which can he used in. combination with a vertically operating draw press of conventional construction to increase its usefulness.

Another object of the invention is to simplify and to reduce the cost: of production of longitudinally curved sheet metal parts having narrow cross sections.

Another object of the invention is; to stretch theusheet material in only a vertical direction, whereby its placing on the die is made less complicated and special clamps for holding the material' are avoided.

Another object of the invention is to provide a balanced adapter structure including a shaft located opposite the die, the shaft having rubber cushions which compensate due to their compres sibility-the stretch. in the work piece to avoid bending forces in the cylinder rams.

' vertical position in the shape of a loop. Both ends of the loop are held. by the standard set of clamps located at one. sid of the platen, wh reas the other endsof the transverse supports, carry a shaft over which are slung rubber cushioned metal. bands, preferably made of steel, held by the other standard. set of clamps located at the.

other side at the platen. so. that th forces acting on the platenproduce. balanced momentums about thecenter oithe platen. By this arrangement work. pieces made. of thin sheet metal can be stretched andv formed. intonarrow cross sections which could. not bedrawn prior tothis. invention, because of the greater width of the platen and the greater distance from. each other of the clamps positioned at opposite sides thereof- For a better understanding of. the inventionreierence should now be had to the a c mp n ng drawings, wherein.

Figure l. is a. fragmentary cross-sectional: view of the invention takenon line 1-1 of Figure t Figure 2 is, a front view taken in. the direction II-JI. of Figure 1,. with a portion shown in section,

Figure 3 isa cross section taken on line. III.-III of Figure. 1,

Figure 4 is a cross-sectional view taken on lin IV- IV of Figure 1 through the center of the transverse supports.

Figure 5isaplan view of Figure 2, and Figure 6;

is a view similar to. Figure 1, showing a modification of the invention.

Although the principles oi the invention are a plicable with a Symmetrical arrangement for two work pieces, one at. each side, the invention is usually employed. in conjunction with only one work piece and'hence it has been so illustrated and'will be so described.

With specificv reference to the form of the in-- vention illustrated in the drawings, the numeral l indicates supportingibeams-I totwo pairs of which are fastened hydraulic. cylinders 2 in each of which is movable a ram 3 provided at its, upper end: with a head 4 on which is slidable a bearing 5 carrying a pivot 6 secured to the rain beam or platen I. Between the hydraulic cylinders 2 is disposed a cylindrical guide 8 also fastened to a pair 01- supporting. beams l and in whichv is slid-.- ablea. stem 9 carrying an eye In in which is,

swingable a pin ll, secured in the ram beam 1. The stem 9 holds the ram beam, swingable about the pin ll, longitudinally in a fixed position, whereas the hydraulic rams 3 raise and lower the ram beam I in either horizontal or longitudinally inclined positions, as desired, and whereby the bearings 5 swingable about the pivots 6 may slide on the ram heads 4. On the supporting beams I at both sides of the rain beam are slidable beams 14 underneath each of which is bolted a nut I5 guided by and between the two supporting beams I and through which passes a spindle 16 turning in the bearing l1, and driven by some hand or electrically driven mechanism (not shown)to move the beams i4 toward or away from each other. On top along the beams H! are secured series of clamps l8 by bolts [9 each series of which usually holds one edge of a metal sheet to be formed over a die.

According to the invention, the ram beam 1 is provided with two spaced transverse draw arms 20 tiltable about pivots 2! secured to brackets 22, which are adjustably mounted by bolts 23 on the ram beam. One end of these arms 20 carries a shaft 24 fixed thereto and over which are laid upon sleeves 25 adjacent each end rubber cushions 26 or the like to resiliently support preferably sheet steel loops 2? both ends of which are held by one or more clamps 18 secured to the one beam 14. Between the other ends of the balancing arms 20 is inserted and swingably fastened thereto by pins 28 screwed'into the arms, the die 29 over which is looped the metal sheet S to be stretch-formed. The ends of the loop are held by one or more clamps l8 secured to the other beam I4. Usually the arms 20 are made longer on theshaftsi-de than on the die side to reduce the force pressing against the cushion. Instead of making the arms tiltable, they may be immovably fastened directly to the ram beam and, likewise, the die may be bolted in fixed position to the arms, since by the upward movement of the ram beam the angular position of the die hardly changes in case both, the straps and the die, are slanted in the direction of the clamp opening, but not at all when both are put in vertically. In slanted position the slanting can be so arranged that the transverse components ofthe unequal pulling forces at both sides are equal so that they balance each other and do not tend to bend the pistons and the guide stem. The rubber padding is so made that the amount of its compression approximately corresponds to the stretch of the material to be formed so that least bending stress, if any, is exerted upon the cylinder pistons and the guide stem. By tilting the ram beam during the drawing operation the stretching of the sheet between front and rear can be controlled to a certain extent if necessary.

The operation of the device which can be readily attached to or dismounted from the draw press is extremely simple and practical. When the ram beam is in low position the rubber cushioned resilient steel loops or straps while held in the clamps are spaced from the cushion and sprung outwardly. In this position of the ram beam theinto a permanent shape conforming to that of the die. Due to the fact that the die is held in vertical position, it is so much easier to apply the work material thereto than can be done on especially designed machines for horizontal pull. The advantage of the invention is that it fully serves its purpose and saves the necessity of having an additional press which also occupies valuable floor space for this special work which usually can be done during idle periods of a conventional press available.

It will be recognized, therefore, that a conventional vertically operated draw press equipped with an adapter, according to the invention is a definite improvement, very practical, lowering production cost, and quickly removable when other work is to be done on the press.

While in accordance with the patent statutes one best embodiment of the invention has been illustrated and described in detail, itis to be particularly understood that the invention is not limited thereto or thereby, but that the inventive scope is defined in the claims.

I claim: 7

1. In combination with a conventional sheet metal draw press, including a vertically movable hydraulically operated ram beam and vertically immovable but laterally adjustable clamping means at both sides of said ram beam, a die adapter consisting of a pair of adjustably spaced draw arms secured to and extending at both sides of said ram beam, a shaft connecting and being supported by the ends at one side of said arms, resiliently cushioned holding-down-means between said shaft and one set of said clamping means, anda form die of smaller width than that of the ram beam held between the other ends of said arms for stretching and forming a work sheet in looped condition over said die and held at its opposite edges between the other set of said clamping means.

2. In combination with a conventional sheet metal draw press, including a'vertically movable hydraulically operated ram beam and vertically immovable but laterally adjustable clamping means at both sides of said ram beam, a die adapter consisting of a pair of adjustably spaced draw arms pivotally mounted to and extending'at both sides of said ram beam, a shaft connecting and being supported by the ends at one side of said arms, resiliently cushioned holding-downmeans between said shaft and one set of said clamping means, and a form die of smaller width than that of the ram beam pivotally mounted between the other ends of said arms for stretching and forming a work sheet in looped condition over said die and held at its opposite edges between the other set of said clamping means.

3. In combination with a conventional sheet metal draw press, including a vertically movable hydraulically operated ram beam and vertically immovable but laterally adjustable clamping means at.both sides of said ram beam, a die' adapter consisting of a pair of adjustably spaced draw arms secured to and extending at both sides of said ram beam, a shaft connecting and being.

supported'by the ends at one side of said arms,

a rubber cushion covering said shaft, a sheet metal loop surrounding said cushionand having:

said clamping means, the compression of said cushion being approximately as great as the stretching of the material.

' 4. In combination with a conventional sheet metal draw press, including a vertically movable hydraulically operated ram beam and vertically immovable but laterally adjustable clamping means at both sides of said ram beam, a die adapter consisting of a pair of adjustably spaced draw arms secured to and extending at both sides of said ram beam, but more at one side than at the other, a shaft connecting and being supported by the longer arm extensions, resiliently cushioned holding-down-means between said shaft.

and one set of said clamping means, and a form die held between the shorter arm extensions for stretching and forming a work sheet in looped condition over said die and held at its opposite edges between another set of said clamping means.

5. In combination with a conventional sheet metal draw press, including a vertically movable hydraulically operated ram beam and vertically immovable but laterally adjustable clamping means at both sides of said ram beam, a die adapter consisting of a pair of adjustably spaced draw arms secured to and extending at both sides of said ram beam, and identical form dies between the ends of said arms at both sides and equally distant from the center of the ram beam for stretching and forming, work sheets in looped condition over said dies and held at their opposite edges between said clamping means.

6. In combination with a conventional sheet metal draw press, including a vertically movable, hydraulically operated ram beam and vertically immovable, but in their position laterally adjustable clamping means at both sides of said ram beam, and a die adapter transversely disposed and pivotally supported by said ram beam on an axis substantially at right angle to the axis of ram movement, said adapter acting in cooperation with said clamping means and adapted to stretch and form a looped metal sheet in substantially vertical direction whereby the forces acting at both ends of the adapter substantially equalize each other.

7. In combination with a conventional sheet metal draw press, including a verticallymovable, hydraulically operated ram beam and vertically immovable, but in their position laterally adjustable clamping means at both sides of said ram beam, a pair of spaced transverse die supports extending in opposite directions from said ram beam, a connecting beam carried by one side of said die support, resilient suspension members loosely attached to said connecting beam and held by one set of said clamping means, and a 6 forming die carried by the other end of said die supports for stretching and forming a work sheet in looped condition over the forming die with its free edges held by another set of said clamping means.

8. In combination with a conventional sheet metal draw press, including a vertically movable, hydraulically operated ram beam and vertically immovable, but in their position laterally adjustable clamping means at both sides of said ram beam, a pair of spaced transverse die supports extending in opposite directions from said ram beam, a connecting beam carried by one side of said die support, resilient suspension members slippable over and loosely attached to said connecting beam and held by one set of said clamping means, and a forming die carried by the other end of said clamping means a work sheet in looped condition over the forming die with its free edges held by another set of said clamping means.

9. In combination, a base, a ram beam, means for moving the ram beam away from the base, a set of clamp-s associated with the base on each side of the ram beam, a die, means mounting the die on the ram beam so that the die is positioned to one side thereof substantialy in alignment with one set of clamps, and counterbalancing means positioned between the set of clamps on the other (side of the beam and the means mounting the 10. In combination, a die, beam means mounting the die adjacent one end of the beam means, a hold-down secured adjacent the other end of the beam means, clamping means in substantial alignment with the die, means pivotally supporting the beam means between its ends, and means for effecting relative movement of the beam supporting means with respect to the clamping means and hold-down so as to stretch material over the die when held by the clamping means.

EARL M. WELSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 902,716 Cross Nov, 3, 1908 1,812,726 Stevens June 30, 1931 2,123,683 Oeckl July 12, 1938 2,163,531 Wettstein June 20, 1939 2,245,723 Salzmann June 17, 1941 2,279,964 Berliner Apr. 14, 1942 2,342,437 Summers Feb. :22, 1944 2,346,213 Flowers Apr. 11, 1944 

